Work done to overcome this problem in the standard quantum theory began with the early many-time efforts of P. Weiss [1]} and Dirac [2]}. These ideas were later further developed by Dirac [3]}, and were adopted by others, such as S. Tomonaga [4]} and J. Schwinger [5]} in their approaches to a fully covariant quantum theory. Collectively, these initial works could be characterized as precursors for the subsequent covariant Hamiltonian methods developed, again, by Dirac [6]}[7]}, but which were later refined by K. Kuchař [8]} and C. Teitelboim [9]}[10]} in their pursuit of a covariant approach to geometrodynamics.
